Improving the energy resolution of bent crystal X-ray spectrometers with position-sensitive detectors

A new measurement technique for X-ray spectrometers equipped with a position-sensitive detector is introduced. It is based on the computational compensation of the effects of internal stress of curved analyser crystals to improve the energy resolution in the measurements of point-like samples with no loss of intensity.
Wavelength-dispersive high-resolution X-ray spectrometers often employ elastically bent crystals for the wavelength analysis. In a preceding paper [Honkanen et al. (2014). J. Synchrotron Rad. 21, 104–110] a theory for quantifying the internal stress of a macroscopically large spherically curved analyser crystal was presented. Here the theory is applied to compensate for the corresponding decrease of the energy resolution. The technique is demonstrated with a Johann-type spectrometer using a spherically bent Si(660) analyser in near-backscattering geometry, where an improvement in the energy resolution from 1.0 eV down to 0.5 eV at 9.7 keV incident photon energy was observed.